There are thought to be around 1,500 of the networks in operation in the UK, which involve urban dealers forcing children to carry drugs to customers in more rural areas.
They also take over, or 'cuckoo', the homes of vulnerable or drug-addicted people to use to stash illegal substances.
Dozens of police forces across the UK took part in action last week and 58 victims who had been caught up in the gangs were rescued.
In West Yorkshire, weapons, cash and illegal drugs have been seized during the week of action, with officers making 16 arrests and saving 22 potential victims from the gangs' activities.
Detective Chief Inspector Carl Galvin, Director of Intelligence for West Yorkshire Police, led the operation.
He said: "What is often forgotten when we talk about county lines crime is that there are victims at the centre of it. Hardened criminals are using children or other vulnerable people to do their illegal work.
“The criminal exploitation takes many forms – the most common being criminals targeting the children who may be after ‘easy’ money, is willing to co-operate and who may be keen to find a place where they ‘fit in’ as they grow and develop their own identity.
“Once the children ‘are in’ they are intimidated with threats of violence against them and their loved ones. In short they feel ‘trapped’
“I am particularly pleased, therefore, that we directly safeguarded a number of vulnerable people through our enforcement work (all adults) and delivered resources in schools to warn children and those working with them, of the potential dangers of county lines involvement."
Last Friday, North Yorkshire Police revealed it had arrested 15 people as part of the county lines crackdown, including those from Merseyside, Manchester and Bradford.
Police in Scarborough later arrested four more people.
And last Wednesday (October 10), officers leading the dedicated county lines crackdown Operation Duxford in Barnsley recovered thousands of counterfeit cigarettes and drugs in warrants across the district.
They arrested 10 people, seized a knuckle duster and recovered stolen property.
The National Crime Agency said every force in England and Wales has reported some form of county lines activity.
Weapons including a loaded gun, an axe, a meat cleaver, hunting knives and a samurai sword were also recovered, as well as tens of thousands of pounds in cash, and drugs including heroin and crack cocaine.
Those arrested included criminals already serving prison sentences who were charged with involvement in the supply of class A drugs from behind bars.
The new National County Lines Co-ordination Centre, set up in September, is mapping the activities of the gangs, which are mainly based in large cities such as London, Liverpool and Birmingham, but operate all over the country.
They commonly use one phone line - that can make up to £5,000 per day - which drug users ring to order illegal substances.
Sue Southern, county lines lead for the National Crime Agency, said: "Supply gangs are responsible for high levels of violence and the exploitation and abuse of vulnerable adults and children, and every territorial police force in England and Wales has now reported some level of county lines activity.
"There are currently hundreds of live county lines investigations across the UK, and this period of intensification highlights the range of co-ordinated activity taking place to identify perpetrators, reduce violence, take away the proceeds of crime and safeguard the vulnerable.
"While these operations will have substantially disrupted numerous county lines, our work is ongoing and we are pursuing all available means of strengthening the national response."